At 3.5 miles wide and 400 feet tall, Dry Falls was once the greatest waterfall in the world. Niagara–one mile wide and 165 feet tall–is only a quarter of that size. The falls were powered by Ice Age floods 15,000 years ago; a massive glacial dam collapsed and sent a 3,000-square-mile lake, once covering northwest Montana, hurtling toward the Pacific. Water rushed at 65 miles per hour over the crescent-shaped precipice for several thousand years. Today, a towering basalt plateau remains–and an oasis of desert lakes.

The Way

Hop on the Umatilla Rock Trail in Sun Lakes-Dry Falls State Park two hours east of Spokane. This 2.6-mile path climbs 300 feet to the top of Dry Falls and loops around a tall rock outcropping, named after the native Umatilla. The trail blends into the shrubby, craggy landscape, making it hard to follow in places. At the top, you'll stand 600 feet above what was once a plunge pool where swirling currents carved a natural lake. parks.wa.gov

More than 60 sandstone caves and crevices in Devil's Den State Park shelter thousands of bats. Of the seven species here, the most notable (and scary looking) is the endangered Ozark big-eared bat. Standing less than four inches tall, this flying mammal sports one-inch ears that sprout from the center of its forehead like butterfly wings. The ears are held erect except during hibernation, when they roll up like window shades. The bat's bulbous snout, coupled with the ears, create an appearance both sinister and comical.

The Way

The park, named for its relentlessly rugged terrain, is 25 miles southwest of Fayetteville. From the visitor center, pick up the 1.5-mile Devil's Den Trail. This winding oak- and hickory-lined path takes you to the park's namesake cave, which you'll enter through a thin sandstone crevice. Pack a headlamp and listen for high-pitched screeches, similar to a warbler's call, to locate bats on the ceiling. Steer clear of the cave's mouth at dusk, when bats emerge en masse to scavenge for food. arkansasstateparks.com/devilsden

The Wonder Witch hazel, used as an astringent, has pale yellow blossoms that flower in late fall. More gawk-worthy is the small tree's exploding fruit. The fuzzy brown pod contains two chambers, each protecting a glossy black seed with an edible white interior. Upon maturity, the chambers burst open with an explosive crack, ejecting the seeds up to 10 feet. The fruit and flowers appear at the same time, meaning you could get popped.

The Way Park at Mountain Crossings at Walasi-Yi, a gear shop in Neels Gap, to pick up the Appalachian Trail for a four-mile out-and-back to Blood Mountain. You'll gain 1,800 feet out of the valley. About halfway to the summit, you'll catch the overpowering scent of citrus, indicating a grove of 10-foot-high witch hazel trees lining the path. fs.fed.us/conf/rec/fow/20041130-fow.shtml